What ecological role did South American isolation allow endemic ungulates like *Macrauchenia* to fill in contrast to other continents?

Answer

Ecological niches occupied by rhinos or camels elsewhere

Due to isolation, endemic mammals diversified into unique forms, filling ecological niches that were occupied by rhinos or camels in North America and Eurasia.

What ecological role did South American isolation allow endemic ungulates like *Macrauchenia* to fill in contrast to other continents?
animalextinctmammalmacraucheniarelative